Improved AR waveguide hologram model for accurate exit pupil expander simulation using the RCWA method

Diffractive optical devices are essential in developing compact and thin augmented reality (AR) devices. Surface-reliefgratings (SRG) and volume-holographic gratings (VHG) are typical gratings with periodic material changes. VHG is relatively easy to manufacture, making it a popular choice for R&D teams developing AR exit pupil expander (EPE) applications. In the past, the Kogelnik algorithm was combined with the Ansys Zemax OpticStudio ray tracing engine to simulate VHG for AR applications. However, due to its more approximate calculations, the accuracy of this method is lower than that of the rigorous coupled wave analysis (RCWA) method. This study aims to investigate the theoretical differences between the Kogelnik and RCWA methods, implement their algorithms in practice, and compare the accuracy of the two methods for AR EPE applications using the Zemax OpticStudio ray tracing engine.